diff options
Diffstat (limited to 'patches/sched-core-Remove-get_cpu-from-sched_fork.patch')
| -rw-r--r-- | patches/sched-core-Remove-get_cpu-from-sched_fork.patch | 87 |
1 files changed, 0 insertions, 87 deletions
diff --git a/patches/sched-core-Remove-get_cpu-from-sched_fork.patch b/patches/sched-core-Remove-get_cpu-from-sched_fork.patch deleted file mode 100644 index 5f2c036af9a8..000000000000 --- a/patches/sched-core-Remove-get_cpu-from-sched_fork.patch +++ /dev/null @@ -1,87 +0,0 @@ -From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> -Date: Fri, 6 Jul 2018 15:06:15 +0200 -Subject: [PATCH] sched/core: Remove get_cpu() from sched_fork() - -[ Upstream commit af0fffd9300b97d8875aa745bc78e2f6fdb3c1f0 ] - -get_cpu() disables preemption for the entire sched_fork() function. -This get_cpu() was introduced in commit: - - dd41f596cda0 ("sched: cfs core code") - -... which also invoked sched_balance_self() and this function -required preemption do be off. - -Today, sched_balance_self() seems to be moved to ->task_fork callback -which is invoked while the ->pi_lock is held. - -set_load_weight() could invoke reweight_task() which then via $callchain -might end up in smp_processor_id() but since `update_load' is false -this won't happen. - -I didn't find any this_cpu*() or similar usage during the initialisation -of the task_struct. - -The `cpu' value (from get_cpu()) is only used later in __set_task_cpu() -while the ->pi_lock lock is held. - -Based on this it is possible to remove get_cpu() and use -smp_processor_id() for the `cpu' variable without breaking anything. - -Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> -Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> -Cc: Linus Torvalds <torvalds@linux-foundation.org> -Cc: Peter Zijlstra <peterz@infradead.org> -Cc: Thomas Gleixner <tglx@linutronix.de> -Link: http://lkml.kernel.org/r/20180706130615.g2ex2kmfu5kcvlq6@linutronix.de -Signed-off-by: Ingo Molnar <mingo@kernel.org> ---- - kernel/sched/core.c | 13 ++++--------- - 1 file changed, 4 insertions(+), 9 deletions(-) - ---- a/kernel/sched/core.c -+++ b/kernel/sched/core.c -@@ -2317,7 +2317,6 @@ static inline void init_schedstats(void) - int sched_fork(unsigned long clone_flags, struct task_struct *p) - { - unsigned long flags; -- int cpu = get_cpu(); - - __sched_fork(clone_flags, p); - /* -@@ -2353,14 +2352,12 @@ int sched_fork(unsigned long clone_flags - p->sched_reset_on_fork = 0; - } - -- if (dl_prio(p->prio)) { -- put_cpu(); -+ if (dl_prio(p->prio)) - return -EAGAIN; -- } else if (rt_prio(p->prio)) { -+ else if (rt_prio(p->prio)) - p->sched_class = &rt_sched_class; -- } else { -+ else - p->sched_class = &fair_sched_class; -- } - - init_entity_runnable_average(&p->se); - -@@ -2376,7 +2373,7 @@ int sched_fork(unsigned long clone_flags - * We're setting the CPU for the first time, we don't migrate, - * so use __set_task_cpu(). - */ -- __set_task_cpu(p, cpu); -+ __set_task_cpu(p, smp_processor_id()); - if (p->sched_class->task_fork) - p->sched_class->task_fork(p); - raw_spin_unlock_irqrestore(&p->pi_lock, flags); -@@ -2393,8 +2390,6 @@ int sched_fork(unsigned long clone_flags - plist_node_init(&p->pushable_tasks, MAX_PRIO); - RB_CLEAR_NODE(&p->pushable_dl_tasks); - #endif -- -- put_cpu(); - return 0; - } - |